1. Technical Field
This invention relates to a switching DC-DC converter (hereinafter referred to as a DC-DC converter) which has a overcurrent protection feature and generates an output voltage by the constant voltage control of changing the frequency according to a load condition.
2. Description of the Related Art
A DC-DC converter reduces an output voltage when the DC-DC converter enters an overcurrent operation due to an increase in a load current. When the output voltage has lowered greatly, the DC-DC converter lowers the switching frequency to prevent the overcurrent value from increasing. An example of the DC-DC converter is disclosed in JP-A-10-229674.
In order to improve the efficiency when the load is low, another DC-DC converter lowers the switching frequency, thereby reducing the loss of a power switch due to switching. An example of another DC-DC converter is disclosed in JP-A-9-98571.